use a null timeout instead of an infinite one for testing if a fd is readable on windows
use a null timeout instead of an infinite one for testing if a fd is readable on windows

Ignore-this: b44fbc74196f7ad0d18bbe3d0691edf7

darcs-hash:20120120153716-c41ad-9447f2a8a6072f36e848965dcbe01d9e5a57f5b1

c-cube/lwt,mirage/lwt,gfxmonk/lwt,mirage/lwt,rneswold/lwt,rgrinberg/lwt,rgrinberg/lwt,janestreet/lwt-async,rgrinberg/lwt,gfxmonk/lwt,mfp/lwt,janestreet/lwt-async,ocsigen/lwt,mfp/lwt,fdopen/lwt,fdopen/lwt,rneswold/lwt,ocsigen/lwt,rgrinberg/lwt,c-cube/lwt,rneswold/lwt,c-cube/lwt,ocsigen/lwt